The strategic goal of this research is to improve scientific understanding of coral reef ecosystems throughout the Pacific, and serve as the basis for improved conservation and resource management. The recent designation of the Pacific Remote Islands Marine National Monument highlights the importance of this research.

With their extremely isolated location, many of the Pacific Remote Island Areas host a vibrate marine ecosystem.Previous Pacific RAMP cruises have documented relatively high coral cover and diversity; and high densities of large-bodied reef fish including large numbers of apex predators such as Grey Reef Sharks (Carcharhinus amblyrhynchos) and Scalloped Hammerhead sharks (Sphyraena lewini). Many of these apex predators are rare near human population centers. AS in previous years, this Pacific RAMP cruise will perform a suite of standardized multi-disciplinary methods which include Rapid Ecological Assessments (REA) for fish, corals, other large invertebrates, and algae; towed-diver surveys for large-bodied fish and habitat composition; and oceanographic studies, which include the measurement of conductivity, temperature, and density of the water column (CTD casts); water sampling; and deployment of sea-surface temperature (SST), subsurface temperature recorders (STR) and acoustic doppler current profilers (ADCP).Scientists will also be deploying Ecological Acoustic Recorders (EARs) to learn about changes in the presence and activity of marine mammals, fish, crustaceans and other sound-producing marine life when researchers aren't there to record it otherwise. Autonomous reef monitoring structures (ARMS) will also be deployed as part of the CReefs project. ARMS are simple, standardized collecting structures designed to roughly mimic the structural complexity of reef habitats.They allow for the identification of small, hard-to-sample, but ecologically important cryptic invertebrates. ARMS are being utilized throughout the Pacific and globally to systematically assess spatial patterns and temporal changes ofbiodiversity.Use of the EARS and ARMS are an exciting addition to RAMP data collection efforts.

Follow along below to learn more about where we are going, what we are seeing, and what we have found ...

Friday, April 30, 2010

The Hi'ialakai returned safely to port in Honolulu on Sunday, April 24 at 0800 bringing a very successful completion to HA1001, the 2010 Pacific RAMP expedition to Johnston Atoll, the Phoenix Islands, American Samoa, and the Line Islands. All told, we had the participation of 44 scientists from eight different research institutions and local and regional management organizations. We visited 13 islands, reefs, or banks and were once again amazed by the diversity of life found beneath the waves.

In the days since the ship returned to port we have been offloading equipment and getting everything back to its rightful place, ready for our next expedition to the Northwestern Hawaiian Islands in September of 2010. We want to thank everyone who followed along with our expedition and especially those of you who wrote in with your questions and comments. We hope that we have been able to answer most of them and look forward to hearing from you again on future expeditions.

With that, we will sign off for now. As the Northwestern Hawaiian Islands expedition begins, we will host a new blog and will post the address both here and on the CRED FaceBook page where you can follow-along with all of the most up-to-date information on our program.

Thursday, April 22, 2010

How can scientists get a better sense of what’s living on the bottom or swimming above coral reefs on an island-wide scale? Detailed surveys examining benthic and fish assemblages at specific sites are one way; however, if you're interested in a fast, effective, and extensive method for assessing and monitoring coral reef health over a large spatial scale, towed-diver surveys are for you.

The towed-diver survey methodology is a unique and integrated data collection method for mesoscale assessment of benthic coral reef habitats. The method utilizes SCUBA divers pulled behind a small boat at depth, covering enormous areas of terrain each day, sometimes surveying close to 18 hectares (18 kilometers x 10 meter survey swath). Multiply that out over a 30-day cruise and you can imagine what the towed-diver team sees!

What’s on a towed-diver board? Benthic divers have a bottom-mounted camera that collects still photographs of the benthic habitat every 15 seconds, while fish divers have a video camera that records forward-facing video for the duration of the 50-minute survey. Temperature and depth are recorded every 5 seconds throughout the survey (cylinder on the left side). Gauges/timers tell the diver how long the divers have been down for, how deep they are, and sound a 5-minute alarm when each survey segment is completed. Finally, both benthic and fish observations are tallied on the datasheet located on the right-hand side of the board.

Towed-divers
typically fly around the entire forereef perimeter of the smaller
islands, and stagger their surveys along larger ones. In some cases,
divers also survey backreef or lagoon habitats (e.g. at atolls) or
terraces.

Towed-diver observational data can be processed
relatively quickly in order to get a general picture of what the reefs
are comprised of (e.g. hard and soft coral cover, stressed coral, algae,
etc.) and what fishes are present, while the processing of
photographic and video data sets occurs back in the lab in Honolulu.
Given the spatial extent of surveys conducted on this cruise, It would
be impossible to convey everything recorded thus far; however, here are a
few of the benthic highlights from each of the island ecosystems:

Jarvis Island

Jarvis was largely dominated island-wide by the
species of hard coral Montipora aequituberculata.

The west side has an extensive population of
Sinularia (soft coral) found nowhere else around the island, extending ~
300 meters north-south at the 50 foot survey depth, and covering nearly
100% of the bottom.

Live, branching Pocillopora and Acropora coral
fragments were found along the south-facing shore, suggesting a recent
weather/wave event.

Images obtained from towed-diver surveys of Jarvis Island: Montipora
aequituberculata , left panel; Sinularia dominance on the western side of the island,
upper right panel; Broken Pocillopora colonies, lower right panel

Palmyra Atoll

While towed-diver surveys recorded localized
proliferation of a number of hard coral genera, the majority of benthic
segments were dominated by a species of Porites along the forereef and
western terrace.

Low levels of bleaching were observed within numerous genera around Palmyra; additional analysis of towed-diver photographs
will further explore the extent of coral bleaching around the atoll..

Hard and soft coral cover varied between habitats, and varied depending upon depth and exposure to wave energy. However, overall hard coral cover for all pooled surveys was nearly identical as all pooled surveys around Palmyra.

The southeastern backreef continues to harbor the highest concentration of giant clams (Tridacna spp.) of anywhere we surveys around the Pacific.

The east-side backreef adjacent to the shipwreck showed a dramatic increase in cyanobacteria at 50’ – 60’ since the previous 2008 surveys, along with the presence of a fish aggregation device (FAD) not seen before.

Images obtained from towed-diver surveys of Kingman Reef. Fish Aggregation Device (FAD) seen from below, left panel; Cyanobacteria bloom near the
shipwreck , middle panel; Giant Clams along the southeastern backreef, right panel

Tuesday, April 20, 2010

We have received some great questions pertaining to the April 6th blog post entitled "Predator Dominated Reefs". It's always good to know people are intrigued and interested in our research; please feel free to keep the questions coming!

Question 1: How will global warming impact Jarvis Island?

Response by Jason Helyer, Coral Reef Specialist

This is a great question, but a difficult one to provide a straight forward answer for. Some researchers believe that the cold, nutrient-rich waters that bathe the west side of Jarvis (see blog post “Questions pertaining to the Oceanography of Jarvis Island” regarding upwelling at Jarvis) may provide biological communities at Jarvis protection from climate change associated impacts. In other words, if adjacent ocean temperatures rise, the waters around Jarvis may remain cooler thanks to upwelling associated with the EUC. This cooler water could provide protection to corals at Jarvis from bleaching from rising sea surface temperatures associated with global warming. But this is just a thought shared by some scientists and we really do not know how the oceanographic conditions around Jarvis might change with a changing climate. For example, if the EUC changed as a result of a changing climate, either weakening or deepening, the effects at Jarvis could be substantial as the impact of the current on the oceanographic conditions at Jarvis is a dominant feature structuring the reef community. This uncertainty makes it difficult to answer large questions about how systems might change from global warming and is one of the main reasons why it is important to monitor both biological and physical processes at these remote reefs.

Question 2: In reference to your post that "Jarvis has about 300 times more predatory fish biomass than the entire island of Oahu." What are the factors that reduce the predatory fish volumes in Oahu?

Response to this question as well as the following are by Brian Zgliczynski,
Fish Biologist

There are multiple factors that negatively impact populations of predatory fishes. They include fisheries extraction, pollution, and habitat loss. However, fisheries extraction has been shown to have the most deleterious effect on the abundance and biomass of predatory fishes globally. Artisanal, commercial, and recreational fisheries typically target large-bodied commercially-valuable fishes that play an important role in structuring marine ecosystems. As large-bodied species are removed from the system the abundance and biomass of large-bodied predatory species available in the system is reduced.

Question 3: Does illegal fishing occur in the waters around Jarvis and what impact does it have on the trophic pyramid?

Jarvis is one of the most remote and isolated islands under U.S. jurisdiction. This geographic isolation affords Jarvis some protection from anthropogenic disturbances including fisheries. However, this same geographic isolation makes Jarvis potentially vulnerable to illegal fishing activities. As fish populations near inhabited coastal areas are reduced, the threat of commercial fisheries moving offshore to exploit resources at remote and uninhabited islands like Jarvis can become a reality. Fortunately, Jarvis has been designated as a National Marine Monument and is managed and protected under U.S. law out to the 50 nautical mile boundary. This designation provides the necessary legal protection and technologies are being developed to monitor and enforce the Monument boundaries. To date, we have not observed any signs of illegal fishing activities during our biennial reef assessment and monitoring efforts.

Question 4: How does the percentage of predatory biomass at Jarvis compare to Cocos
Islands and other areas with high levels of predatory biomass?

Having conducted similar surveys throughout the tropical Pacific
including Cocos Island (Costa Rica), the predatory biomass densities
observed at Jarvis are among the highest. Additionally, all of the sites
where predatory species are abundant display similar inverted trophic
pyramids with predatory species accounting for the largest proportion of
total fish biomass.

We received a question by Reille related to the blog post entitled "The Oceanography of Jarvis Island" written by Jamison Gove on 3-April-2010.

Response by Jamison Gove, Oceanographer and Chief
Scientist of the current
expedition

Great questions Riell! I'll do my best to answer them appropriately, but if you would like more detail on the oceanographic conditions at Jarvis Island, see Gove et al (2006) Temporal variability of current-driven upwelling at Jarvis Island

Question 1: You mention that "few places on the planet have the oceanographic and coral reef environment that is found at Jarvis" could you tell me what other places in the Pacific have both the oceanographic features and the high-productivity coral reef that Jarvis does?

Due to the remote nature of the central equatorial Pacific, I imagine there may be a few islands that have similar ecosystem dynamics as those observed at Jarvis; however, it is the particular location and shape of Jarvis Island which facilitates its oceanographic and biological uniqueness, and when combined with limited human presence over the past half-century, it remains a rarity.

Question 2: I guess something similar happens around the Galapagos and that is a result of the Cromwell Current, as well, but how does the situation there compare to the oceanographic conditions at Jarvis?

They two island ecosystems are comparable as the Equatorial Undercurrent (a.k.a. Cromwell Current) fuels the high productivity at both the Galapagos and Jarvis. That being said, fundamentally different physical oceanographic dynamics occur between the two ecosystems. At the latitude of Jarvis Island, the EUC is flowing incredibly fast for an open ocean current (~1 meter/second) at a depth of 100-150 meters. When this fast moving, subsurface current interacts with Jarvis it results in a cessation of flow, and due to pressure differences, isotherms (lines of equal temperature) are forced vertically upward to the near surface. This island-current interaction driving upwelling is a result of Bernoulli dynamics, which happens to be the very same physical mechanism which gives airplane wings lift.

Due to the upward tilt of the EUC and the thermocline from west to east across the Pacific (see figure below), the EUC is near the surface (0 – 50 meters) at the latitude of the Galapagos Islands. As such, the Galapagos are surrounded by nutrient-rich waters. The productivity at the Galapagos is also enhanced (and therefore my explanation confounded) by natural iron input associated with the geological make-up of the Galapagos Islands, but that’s another question best left for another time.

Side view of the equatorial Pacific showing the Equatorial Undercurrent flowing east along the thermocline. Note the upward tilt of the EUC from the western to the eastern Pacific. Colors indicate relative temperature, with warmer temperatures shown in red and cooler temperatures in blue. Figure modified from http://www.pmel.noaa.gov/tao/

Question 3: I wonder -- does the size of the island result in differences between one side and the other; does the upwelling affect all sides equally?

The upwelling at Jarvis only occurs to the western side of the island, principally due to the fact that the EUC is an eastward flowing current. Surprisingly, there can be a 1-3 ºC difference between the western side of the island and the eastern side (see figure below). Given that Jarvis is only 4 x 2 kilometers, this is a rather substantial gradient in temperature over a very short distance.

Temperature at 25 meters depth around Jarvis obtained from near shore conductivity, temperature, and depth (CTD) casts (locations indicated by triangles). Note the 2.5 degree Celsius difference between the western side and all other sides of the island. Figure taken from Gove et al., 2006.

Question 4: Also, could you briefly describe what kind of seasonal variation you see, or variation in El Niño years, and whether you've yet observed organism behavioral adaptations in relation to any variation?

There is definitely seasonal and interannual variability in upwelling at Jarvis. Seasonally, the strongest upwelling at Jarvis occurs during northern hemisphere spring, due to a locally shallow thermocline and shallow and strong EUC. Year to year differences in upwelling are driven by the strength of the trade winds in the western Pacific and their impacts on flow of the EUC; intensified trade winds associated with La Niña conditions favor the shoaling and strengthening of the EUC at Jarvis, and therefore strong upwelling, while a weakening of the trade winds results in a slackening and deepening of the EUC, diminishing or all together shutting down upwelling. Presumably, this variability would impact local fish and benthic coral reef communities; however, we have yet to analyze the data collected during the current El Niño to confirm this statement

Monday, April 19, 2010

‘Reef Biodiversity: an Introduction’ posted on the 4th of February introduced coral reef diversity and the Autonomous Reef Monitoring Structure (ARMS). This post will explore the recovery and processing of these platforms.

ARMS awaiting removal on left, encapsulated ARMS on right

An ARMS is a tool used to assess the lesser known and cryptic reef organisms. For the past two years, sessile and motile critters have been colonizing the open and closed ARMS layers. One of our missions on this cruise has been to recover all the previously deployed ARMS for immediate shipboard and subsequent land-based processing.

We remove the ARMS from the benthos by attaching a milk crate lined with an 80 micron mesh over the center stack of plates comprising the structure. A buoyed rope is then attached to the latching straps on the crate, and the whole unit is pulled to the surface. The milk crate ensures that any recruited organisms within the ARMS will not fall out during transport. Once on the surface and in the small boat, the milk crate encapsulated ARMS is placed within seawater-filled bins and transported back to the Hi‘ialakai.

Back on the ship, the ARMS is disassembled within a tub of seawater. The milk crate is detached, and each layer (plate) is removed individually. The top and bottom of each plate is photographed to document the sessile organisms. Once photographed, a paint brush is used to lightly sweep any motile organisms off the plates and into a bucket of seawater. The plates are then placed in ethanol to preserve the DNA for future molecular processing.

An example of a plate photograph

Once every layer has been photographed, brushed, and preserved, all of the buckets of seawater used during the processing are sieved into the following bins: 5 mm, 2 mm, 500 ?m, and 100 ?m. The contents from the 2 mm, 500 ?m, and 100 ?m sieves are bulked and placed immediately into ethanol. Selected critters found within the 5 mm sieve are photographed, identified, and preserved individually while the remaining 5 mm organisms are bulked and placed in ethanol.

The final task is to scrape the sessile organisms from the all the plates. The scrapings are bulked and preserved. In this manner, we are able to remove, preserve, and store all of the sessile and motile organisms that have recruited to the ARMS.

When we return to land, the contents will be sent to our partners at the Smithsonian, the Florida Museum of Natural History, and the Hawaiian Institute for Marine Biology who will begin the molecular processing and taxonomic archiving. Genetic sequencing will provide a relative index of diversity for each of our survey sites. We will then be able to compare these indices among and between sites, islands, and regions. Ultimately, this process may allow us to detect and monitor changes in cryptic diversity in an effort to understand ecosystem shifts overtime.

Saturday, April 17, 2010

We have arrived last stop for this expedition, Kingman Reef. Located nearly halfway between American Samoa and Hawaii (1700 km/1056 mi), Kingman is the northernmost reef of the Line Islands. First discovered by Captain Edmund Fanning in 1798 it was later described in 1953 by the island’s namesake Captain W.E. Kingman. Other pre-twentieth century names for Kingman include Danger Reef, Cladew Reef, Maria Shoal and Crane Shoal. In 1856 Kingman Reef under the name “Danger Reef” was claimed by the US as part of the Guano Islands Act. Kingman was later formally annexed 1922 as an unincorporated U.S. possession of the United States.

The only emergent land at Kingman; a narrow strip of coral rubble and coarse sand

The lagoon at Kingman Reef was used as a halfway stop for Pan American Airways flying boats in 1937 and 1938 for flights between Hawai’i, American Samoa, and New Zealand. To facilitate this overnight stop a supply ship was stationed at Kingman to provide fuel, lodging and meals. After a fatal explosion shortly after take off from Pago Pago in January 1938, Pan Am stopped flights to New Zealand via Kingman Reef and Pago Pago. A new route was later established through Canton Island and New Caledonia. In 1941 the US Navy assumed control of Kingman and maintained its jurisdiction until 2000. Kingman Reef was established as a National Wildlife Refuge on January 18, 2001. On January 6, 2009 Kingman Reef was designated as part of the Pacific Remote Islands Marine National Monument.

A cluster of Giant Clams (Tridacna maxima ) at Kingman Reef

Kingman Reef is an uninhabited, triangular shaped reef that is mostly submerged. A small, single strip of “dry land” composed of mainly of dead and dried coral skeletons, is located on the eastern rim of the reef. With the highest point of land at approximately 1 meter, the island is often awash during high tide and is inhospitable for most organisms. Despite the harsh surface conditions Kingman Reef supports a vast variety of marine life below. Approximately 130 species of corals are known at Kingman and giant clams are abundant in shallow waters. Predators dominate the waters at Kingman similarly to most of the uninhabited islands we visit.

Oceanographer Chip Young surveys the reef at Kingman

We’ll be here for the next 6 days conducting our standard suite of work before beginning the transit home.

Jarvis Island National Wildlife Refuge
(NWR) has something to offer everyone. As you can see by exploring
previous blog entrees, the underwater world is exceptional by any
standard. However, if you were to crawl out of the water, up onto and
over the coral rubble that forms the beach, you would see a dazzling
view of life on dry land equaling that of the surrounding coral reef
community. After days on the open ocean all of your senses would be
simultaneously assaulted by the sound of thousands of nesting seabirds,
the sight of verdant island vegetation and the fragrance of
life, reproduction and death. You see, Jarvis Island, only a little
over one thousand acres in size, is the only land within thousands of
square miles of open ocean. As such, this island provides the only
suitable conditions for as many as 13 or more different seabird species
of birds, in numbers often exceeding several hundred thousand, to mate
and reproduce.

The isolated nature of Jarvis Island (> 200 miles from the next
nearest island) makes visitation difficult and is generally accomplished
only once every two years. On 01 April, two members of the US Fish and
Wildlife Service, Jiny Kim and Chris Depkin, were dropped off on the
north-west shore of the island. They spent the next 5 days and 4
nights exploring the terrestrial environs for the purpose of assessing
the state of the seabird communities, looking for signs of unauthorized
human presence, identifying and neutralizing any hazards to wildlife,
mapping and inspecting the island’s vegetation communities for changes
in distribution patterns and looking for recent, non-native plant
introductions.

A White Tern
(Gygis alba) finds
a perch to view its surroundings

Jarvis Island supports very few
plant species most of which are low growing. There are no trees on the island. During previous
visits, plant species were described as brown, and dried with little
flowering, dead or not detected at all. Our first impression of the
island was astonishment and wonder at both the diversity and extent of
coverage of the vegetation. Well over half of the island was bright
green with at least 8 species well represented and most either flowering
or in seed, or both.

A Hermit Crab
searches for food

However, conditions favorable for plant growth and
reproduction (excessive rain fall) are not necessarily conditions
suitable for seabird nesting. The unusual amount of rainfall at Jarvis
is likely a result of the recent El Niño-Southern Oscillation event
(ENSO) which can bring about large scale changes in regional weather
patterns once every 3-5 years. These large scale changes, and in
particular changes in sea surface temperature (SST), also affect the
distribution, abundance, availability and predictability of prey items
critical to successful nesting.

The region is just now
emerging from the current El Niño event and our visit to Jarvis seemed
to support the above. Although thousands of seabirds were present during
this visit, the vast majority were in the very early stages of nesting,
either sitting on eggs or standing around, on territory, getting ready. Chris and Jiny documented the presence of very few chicks either alive or dead
(dead chicks indicate earlier breeding attempts that failed) which
indicates little or no nesting has occurred here over the last several
months. Very preliminary and crude estimates suggest there were less
than 150,000 birds present on the island during this visit. Previous
visits place estimates well over one-million birds present during peak
nesting.

After walking
more than 30 miles during the 5 day period, locating and counting
breeding birds and mapping vegetation distributions, Jiny and Chris were
picked up where they were dropped off, not to return for another 2
years.

Jarvis Island is without question a rare
jewel set in the vastness of the Pacific Ocean. On January 6th, 2009,
President George W. Bush established the Pacific Remote Islands Marine
National Monument. Jarvis Island NWR along with Howland and Baker island, Johnston, Wake, and Palmyra Atolls, and Kingman Reef are all
included in this new Marine Monument which contains 86,888 square miles of
mostly open ocean and the above uplands. The areas designated by this
new Monument are used by over 4 million breeding tropical seabirds and at least 10 million more that are pre-breeders or
migrants passing through those waters on their way to Northern and
Southern breeding grounds. Protecting these remote
places cannot be overstated, important not only for the marine and
terrestrial organisms that live there but for the enjoyment, benefit and
educational opportunities afforded future generations.

Friday, April 9, 2010

Leaving Jarvis on our 400-mile northward transit to Palmyra, we’ve again crossed the equator and have arrived at this low-lying atoll. Palmyra is considered a true atoll because it has reefs encircling three sub-lagoons and supporting many islets. Having surveyed the fish populations here in 2006 and 2008, I’m curious to see if the milkfish (Chanos chanos), blacktip reef sharks (Carcharinus melanopterus), humphead wrasse (Cheilinus undulatus), schools of twinspot snapper (Lutjanus bojar), and manta rays (Manta birostris) that I remember will again make their way into my transect to be counted. Palmyra was discovered by the captain of the American ship Palmyra in 1802, but was not claimed until 1862 when ownership was asserted by Captain Zenas Bent and J.B. Wilkinson for the Kingdom of Hawai’i. Although Palmyra was also claimed by United States under the Guano Islands Act of 1856, it was not actively mined as approximately 180 inches of rainfall per year made it too wet for guano accumulation.

A school of RainbowRunner (Elagatis Bipinnulata). Photograph by Danny Merritt

The British also claimed Palmyra in 1889. The Pacific Navigation Company bought Palmyra in 1885 and the company’s interests were conveyed in 1911 to Judge Henry Cooper via petition to the Land Court of the Territory of Hawai’i. Judge Cooper sold all of Palmyra except two islets to the Fullard-Leo family in 1922. In preparation for possible war, the US Navy attempted to lease Palmyra from the Fullard- Leo family in 1938. However, in 1939 the US Congress authorized construction of a naval base at Palmyra, and the US filed suit to annex the atoll. Up to 6,000 servicemen occupied Palmyra Atoll Naval Air Station during the World War II era. In 1947 the US Supreme Court, returned ownership of the atoll to the Fullard-Leo family. The 1959 Hawai’i Statehood Act specifically excluded Palmyra, and by that time US Navy occupation had ceased and all other federal presence at the atoll ended. Subsequently, the atoll remained abandoned except for resident caretakers supported by the Fullard-Leo family.

Manta Ray (Manta birostris),Palmyra Atoll. Photograph by Chip Young

In 2000, Palmyra was purchased by The Nature Conservancy (TNC), and in 2001 the USFWS purchased all of Palmyra from TNC except for the main island (Cooper) and established the Palmyra Atoll National Wildlife Refuge (NWR). In 2006, TNC completed construction of a research station at Cooper Island, where up to 20 scientists and staff can be housed. While we’re here we hope to have the chance to meet with several of the scientists currently on the atoll to discuss our common research goals and find out what their experiences have been working for weeks or months at a time on Palmyra.

Tuesday, April 6, 2010

Typical reef scene at Jarvis Island with large-bodied predatory species
patrolling the reef.

If you could ask any of the scientists aboard the Hi'ialakai to describe what it's like to dive at Jarvis Island, you would hear something like: “mind-blowing, intimidating, exhilarating, intense, eye-opening“. If you heard these words alone you would think we were out here in the central Pacific filming an energy drink commercial, or certainly something other than conducting scientific research. However, this is definitely not the case, and Jarvis Island is all of this, and more. The first thing we notice upon arriving at a dive site are ominous shadows circling below. As we perform pre-dive checks and review survey protocols, you can’t help but wonder what awaits. The few minutes just before a dive can be filled with anticipation, and quite an adrenaline rush.

Predatory species like jacks and sharks
are abundant at Jarvis

Upon entering the water the ecological monitoring team is greeted by numerous predatory fishes such as grey reef sharks (Carcharhinus amblyrhynchos), twinspot snapper (Lutjanus bohar), black trevally (C. lugubris) , and coral grouper (Cephalopholis miniata). Large-bodied predatory species, which are common at Jarvis, are becoming increasingly rare throughout the tropical Pacific with fisheries exploitation exerting direct impact on reef-fish communities. Predatory species play an integral role in structuring coral reefs and the systematic removal of these important species can have detrimental impacts to the ecosystem.

CRED divers conduct surveys recording species composition as well as the number and size of all fishes observed in a predefined area. These data are converted into measures of abundance and biomass and used to estimate fish populations around an island or reef. At Jarvis, predatory species are highly abundant and account for over half of total fish biomass. Reef scenes like the one pictured above are commonplace. To put this into perspective, Jarvis has about 300 times more predatory fish biomass than the entire island of Oahu. The research conducted here has altered our perspective of the typical trophic pyramid in which predators (tertiary consumers) comprise a small fraction of total fish biomass in a reef ecosystem. At Jarvis Island, the trophic pyramid is inverted, with top predators accounting for a majority of fish biomass.

Trophic pyramids with species divided into their respective trophic categories.
Tertiary consumers = top-level predatory species, planktivores = species that
feed on microscopic organisms, Secondary consumers = lower-level carnivorous
species, and Primary consumers = herbivores. The Pyramid to the left represents
a degraded system with few predators (tertiary consumers) while the pyramid to
the right represents what researchers have observed at Jarvis Island,
where predators are highly abundant.

As predator dominated coral reef ecosystems become increasingly rare in most parts of the world, contemporary ecological studies concentrate efforts on systems that have already been degraded. However, Jarvis Island and other U.S. Pacific islands represent some of the remaining examples of ecosystems in their natural state. Such systems provide an ecological baseline and an unprecedented opportunity for marine scientists to understand what ‘pristine’ coral reef ecosystems are like, aiding in the formulation of appropriate metrics necessary for developing effective ecosystem-based management and recovery plans towards the future.

Saturday, April 3, 2010

Grey Reef Sharks often congregate in the tens to hundreds at Jarvis Island

There is an intimate and inseparable link that exists between oceanography and coral reef ecosystems. Ocean waves, currents, temperature, salinity, and nutrient availability are each important and play a significant role in determining not only the diversity and abundance of organisms an a coral reef, but can also dictate the morphology (shape) of coral and algae species and the substrate they inhabit. For example, corals which are consistently battered by ocean waves tend to be low-lying and mound-shaped, lacking the large, delicate and branching structures that are often found in more benign, wave-free environments.

A few Raccoon Butterfly fish
make their way down the reef

In some places around the world, this connection between coral reef ecosystem dynamics and the surrounding environment can be subtle; however, at Jarvis Island this elemental relationship is so abundantly clear you would have to be sound asleep to miss it. In other words, you can actually see oceanography in action.

Schools of small fish are common
at Jarvis Island

Due to its location in the central equatorial Pacific, Jarvis is impacted by a strong, cold, nutrient-rich ocean current flowing below the surface, centered at approximately 150 meters depth. This current, known as the Equatorial Undercurrent, is spawned in the far western Pacific and flows eastward along the equator and across the entire Pacific Ocean. When this fast-moving current interacts with Jarvis Island, it forces deep water to the near-surface, providing copious amounts of nutrients to the surrounding coral, algal, and fish communities. These nutrients are quickly assimilated by the reef community, fueling an astonishingly productive and ecologically vibrant coral reef system. Few places on the planet have the oceanographic and coral reef environment that is found at Jarvis, making it a unique and special place not only for scientific research, but also for protection for many generations to come.

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The mission of the Coral Reef Ecosystem Division is to provide sound science to enable informed and effective implementation of ecosystem-based management and conservation strategies for coral reef ecosystems of the U.S.-affiliated Pacific Islands Region.

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